This was a game that came on the exact same disk as John Romero's "Dangerous Dave", and as you might expect, this game was made by John Carmack, both of whom eventually left Softdisk to form Id Software. Like the Dangerous Dave games, the original Catacomb games are now maintained and sold by Flat Rock Software. This one's always been freeware, though the pseudo-sequel "The Catacomb", the one that comes with a level editor, is not.